28 research outputs found
A survey on passive digital video forgery detection techniques
Digital media devices such as smartphones, cameras, and notebooks are becoming increasingly popular. Through digital platforms such as Facebook, WhatsApp, Twitter, and others, people share digital images, videos, and audio in large quantities. Especially in a crime scene investigation, digital evidence plays a crucial role in a courtroom. Manipulating video content with high-quality software tools is easier, which helps fabricate video content more efficiently. It is therefore necessary to develop an authenticating method for detecting and verifying manipulated videos. The objective of this paper is to provide a comprehensive review of the passive methods for detecting video forgeries. This survey has the primary goal of studying and analyzing the existing passive techniques for detecting video forgeries. First, an overview of the basic information needed to understand video forgery detection is presented. Later, it provides an in-depth understanding of the techniques used in the spatial, temporal, and spatio-temporal domain analysis of videos, datasets used, and their limitations are reviewed. In the following sections, standard benchmark video forgery datasets and the generalized architecture for passive video forgery detection techniques are discussed in more depth. Finally, identifying loopholes in existing surveys so detecting forged videos much more effectively in the future are discussed
A novel and disposable amperometric hydrazine sensor based on polydimethyldiallylamine stabilized copper(II)hexacyanoferrate nanocubes modified screen-printed carbon electrode
© 2017 The Authors. A cubic shaped copper(II)hexacyanoferrate was prepared by wet chemical method by mixing an equimolar concentration of CuCl 2 with K 3 [Fe(CN) 6 ] 2 in the presence of poly(diallyldimethylammonium chloride) (PDDA). The X-ray diffraction, field emission scanning electron microscopy, elementa l analysis, Fourier transform infrared spectroscopy and thermal gravimetric analysis were used to confirm the formation of PDDA stabilized copper(II)hexacyanoferrate nanocubes (PDDA@copper(II)hexacyanoferrate nanocubes). The electrocatalytic behavior of the PDDA@copper(II)hexacyanoferrate nanocubes modified screenprinted carbon electrode (SPCE) towards electrochemical oxidation of hydrazine was studied by cyclic voltammetry (CV). The CV results revealed that PDDA@copper(II)hexacyanoferrate nanocubes modified SPCE exhibits an enhanced electrocatalytic activity and lower oxidation potential towards hydrazine than bare SPCE. Under optimized conditions, amperometric i-t method was used for the determination hydrazine, and PDDA@copper(II)hexacyanoferrate nanocubes modified SPCE can able to detect hydrazine in the linear concentration ranges from 0.03 to 533.6 μM with a detection limit of 10 nM. The PDDA@copper(II)hexacyanoferrate nanocubes modified SPCE is highly selective in the presence of potentially active interfering compounds including high concentration of ascorbic acid. In addition, the developed hydrazine sensor shows acceptable practicality with excellent long-term stability towards the detection of hydrazine
A robust nitrobenzene electrochemical sensor based on chitin hydrogel entrapped graphite composite
© 2017 An amperometric nitrobenzene (NB) sensor has been developed based on a glassy carbon electrode (GCE) modified with the composite of chitin hydrogel stabilized graphite (GR-CHI) composite. The physicochemical characterization confirmed the formation of GR-CHI composite and was formed by the strong interaction between GR and CHI. Furthermore, GR-CHI composite modified GCE was used to study the electrochemical reduction behavior of NB by cyclic voltammetry (CV) and compared with GR and CHI modified GCEs. The CV results confirmed that GR-CHI composite modified electrode has high catalytic ability and lower reduction potential toward NB than other modified electrodes due to the combined unique properties of exfoliated GR and CHI. The GR-CHI composite modified electrode can be able to detect the NB in the linear response range from 0.1 to 594.6 µM with the lower detection limit of 37 nM by amperometric i–t method. The selectivity of the sensor is evaluated in the presence of nitroaromatic, biologically active and dihydroxybenzene compounds. The sensor shows appropriate practicality and good repeatability toward detection of NB in lab water samples
Effect of ammonium based ionic liquids on the rheological behavior of the heavy crude oil for high pressure and high temperature conditions
Heavy crude oil (HCO) production, processing, and transportation forms several practical challenges to the oil and gas industry, due to its higher viscosity. Understanding the shear rheology of this HCO is highly important to tackle production and flow assurance. The environmental and economic viability of the conventional methods (thermal or dilution with organic solvents), force the industry to find an alternative. The present study was constructed to investigate the effect of eco-friendly ionic liquids (ILs) on the HCO's rheology, at high temperature and high pressure. Eight different alkyl ammonium ILs were screened for HCO's shear rheology at the temperatures of 25–100 °C and for pressures 0.1–10 MPa. The addition of ILs reduced the HCO's viscosity substantially from 25 to 33% from their original HCO viscosity. Also, it aids to reduce the yield stress to about 15–20% at all the studied experimental conditions. Furthermore, the viscoelastic property of the HCO was studied for both strain-sweep and frequency-sweep and noticed the ILs helps to increase HCO's loss modulus (G″) by reducing storage modulus (G′), it leads to the reduction of the crossover point around 25–32% than the standard HCO. Mean the ILs addition with HCO converts its solid-like nature into liquid-like material. Besides, the effect ILs chain length was also studied and found the ILs which has lengthier chain length shows better efficiency on the flow-ability. Finally, the microscopic investigation of the HCO sample was analyzed with and without ILs and witnessed that these ILs help to fragment the flocculated HCO into smaller fractions. These findings indicate that the ILs could be considered as the better alternative for efficient oil production, processing, and transportation
Effects of Imidazolium-Based Ionic Liquids on the Rheological Behavior of Heavy Crude Oil under High-Pressure and High-Temperature Conditions
The production, processing, and transportation
of heavy crude oil
(HCO) is difficult because of its high viscosity. For practical applications,
information on the rheological behavior of HCO plays an important
role, especially in flow assurance investigations. In this work, six
different imidazolium ionic liquids (ILs) were tested for their effects
on the rheological behavior of HCO under high-pressure and high-temperature
conditions. The rheological studies were carried out at three different
pressures (0.1, 5, and 10 MPa) and four experimental temperatures
(298.15, 323.15, 348.15, and 373.15 K). The HCO + IL systems showed
favorable viscosity reductions of 26.5% and 31.5% for the systems
of HCO + 1-butyl-3-methylimidazolium chloride ([BMIM]<sup>+</sup>[Cl]<sup>−</sup>) and HCO + 1-octyl-3-methylimidazolium chloride ([OMIM]<sup>+</sup>[Cl]<sup>−</sup>), respectively, at 298.15 K and 0.1
MPa as compared to the pure HCO system. At 298.15 K and 0.1 MPa, the
yield stress of the HCO + IL systems was reduced by about 15–20%,
whereas when the temperature was increased to 373.15 K, the yield
stress decreased in the range of 25–30% as compared to that
of neat HCO. The viscoelastic moduli of the HCO sample at 0.1 MPa,
298.15 K, and about 1.5% strain were found to be <i>G</i>′ (storage modulus) ≈ 11 Pa and <i>G</i>″
(loss modulus) ≈ 7 Pa, indicating that the HCO sample was solidlike,
whereas for the HCO + IL systems, the <i>G</i>′ and <i>G</i>″ values were reduced to ∼7 and 3 Pa, respectively.
The crossover frequency of the HCO + IL systems was reduced to the
range of 25–30% as compared to that of pure HCO. From the various
measurements, it was observed that the addition of the ILs to the
HCO resulted in improved rheological properties compared to those
of the pure HCO system. Further, the results of the microscopic investigation
also supported the rheological studies, indicating that the addition
of the ILs helped to break the large flocculated structures of HCO
into smaller spheres. It was also observed that the IL with the longer
alkyl chain length provided greater efficiency in the viscosity reduction
with favorable viscoelastic behavior
Use of Aromatic Ionic Liquids in the Reduction of Surface Phenomena of Crude Oil–Water System and their Synergism with Brine
Enhanced
oil recovery is governed primarily by the role of interfacial
tension between crude oil and water. Interfacial tension (IFT) of
the crude oil–water system is one of the vital factors in the
analysis of the capillary forces affecting trapped oil within the
reservoir rocks. High salinity and temperature of the reservoirs tend
to make researchers search for new surfactants to lower the interfacial
tension in crude oil–water systems. The current study hopes
to create a move toward solving the above problem through the use
of aromatic ionic liquids (ILs) based on imidazolium as the cation
and various anions such as [Cl]<sup>−</sup>, [Br]<sup>−</sup>, [BF<sub>4</sub>]<sup>−</sup>, [H<sub>2</sub>PO<sub>4</sub>]<sup>−</sup>, [HSO<sub>4</sub>]<sup>−</sup>, and [PF<sub>6</sub>]<sup>−</sup> in different concentrations. This work
involves the study of the effect of concentration, temperature, time,
and brine on the fate of surface tension (SFT) of water and interfacial
tension of crude oil–water systems. The present study also
addresses the trend in the electrical conductivity of ILs in water
along with the effect of temperature and concentration of ILs. The
study reveals that these ILs are effective in reducing the SFT and
IFT of water and crude oil–water systems at high salinity and
temperature conditions. In the IFT measurements, a linear decrement
with increase in temperature is observed for crude oil–water
in the presence of ILs. The interfacial tension of the various imidazolium-based
ionic liquids with the crude oil–water system has been measured
as a function of temperature by means of the Wilhelmy plate method.
The influence of the nature of cation and anion of ionic liquids and
of the chain length on the cationic head of the ILs on interfacial
tension is also discussed in detail. At increased salinity conditions,
unlike classical surfactants, these ILs are found to be more successful.
Enhanced efficiency of the drop in IFT using NaCl and IL mixture has
been confirmed by measuring the IFT between crude oil and the aqueous
solution of IL. The synergism of salt and IL mixture on the reduction
of IFT has been observed
Experimental Investigation on the Effect of Aliphatic Ionic Liquids on the Solubility of Heavy Crude Oil Using UV–Visible, Fourier Transform-Infrared, and <sup>13</sup>C NMR Spectroscopy
Chemical treatment of aromatic heavier
hydrocarbons are traditionally
done by using cyclic aromatic nonpolar solvents, such as benzene,
xylene, and toluene, which have the capability to dissolve asphaltenes.
However, these aromatic solvents are volatile and hazardous and hence
not advisable to use. Alternatively, lighter hydrocarbons, such as
heptane, hexane, etc., show lesser solubility. It is, therefore, crucial
that these problems require intelligent, cost-effective, and innovative
solutions. The present work investigates the possible solution for
the dissolution of heavy crude oil using the application of eight
aliphatic ionic liquids (ILs) along with five solvents, namely, toluene,
heptane, decane, ethyl acetate, and hexane. Ionic liquids (ILs) based
on [CH<sub>3</sub>COO]<sup>−</sup>, [BF<sub>4</sub>]<sup>−</sup>, [H<sub>2</sub>PO<sub>4</sub>]<sup>−</sup>, and [HSO<sub>4</sub>]<sup>−</sup> as anions and with various cations, such
as di- and tri-alkyl ammonium, are considered. The enhancement in
the solubility of heavy crude oil in solvent + ILs mixture is investigated
using Ultraviolet–visible (UV–vis) spectrophotometry,
Fourier transform-infrared spectroscopy (FT-IR), and <sup>13</sup>C-nuclear magnetic resonance (NMR) spectroscopic techniques. The
absorbance of the sample solution (heavy crude oil + solvent + IL)
is compared with the standard solution (heavy crude oil in neat solvent
alone). It is observed that the dissolution of heavy crude oil is
more in the solution with IL than with the solvent alone. Solubility
of heavy crude oil in solvents increases to about 70% in the presence
of ILs. Hold-time study is also performed to understand the maximum
time required for efficient dissolution of heavy crude oil. The hold-time
study reveals that solubility of heavy crude oil in heptane increased
to about 61–222% in the presence of ILs, as compared to 11–16%
in the case of standard solution for a prolonged period of 30 days